refactor: make env setting less hardcoded

src/playbook/Configuration/atlas/start.yml

@@ -30,13 +30,20 @@ actions:
   - !powerShell:
     wait: true
     command: >-
-      [Environment]::SetEnvironmentVariable('Path', $env:Path +
-      """;$env:windir\AtlasModules;$env:windir\AtlasModules\Apps;$env:windir\AtlasModules\Other;$env:windir\AtlasModules\Tools;%windir%\AtlasModules\Scripts""",
-      [System.EnvironmentVariableTarget]::Machine);
+      $modulesPath = """$env:windir\AtlasModules""";
 
-      [Environment]::SetEnvironmentVariable('PSModulePath', $env:PSModulePath +
-      """;$env:windir\AtlasModules\Scripts\Modules""",
-      [System.EnvironmentVariableTarget]::Machine)
+      function AddToVar($env, $value) {
+            $a = [IO.Path]::PathSeparator;
+            $b = [System.EnvironmentVariableTarget]::Machine;
+            $c = [Environment]::GetEnvironmentVariables($b);
+
+            [Environment]::SetEnvironmentVariable($env,
+            ("""$($c.'Path');$value""" -replace ';',"""$a"""),
+            $b);
+      };
+
+      AddToVar 'Path' """$modulesPath;$modulesPath\Apps;$modulesPath\Other;$modulesPath\Tools;$modulesPath\Scripts""";
+      AddToVar 'PSModulePath' """$modulesPath\Scripts\Modules""";
 
     # Doesn't refresh the environment variables of TrustedUninstaller
     # An alternative should be found, for now, exact paths are used